limit_container_types can't/won't filter certain vars

limit_container_types works on a var like cinder_backends as follows:

container_vars:
  cinder_backends:
    limit_container_types: cinder_all

It only applies the var to hosts that match the filter.

limit_container_types doesn't get applied to "container_vars" though, so you can't filter all vars in container_vars.

Additionally, some vars can't be filtered, for example "glance_nfs_clients" because it is a list of dicts, so the following won't be filtered:

container_vars:
  limit_container_types: glance_all
  glance_nfs_clients:
    - key1: v1
      key2: v2

And the following is invalid syntactically:
container_vars:
  glance_nfs_clients:
    limit_container_types: glance_all
    - key1: v1
      key2: v2

It seems limit_container_types should apply on the container_vars level - but don't, so it's not possible to filter all vars.